WASHINGTON — Gun homicides have dropped steeply in the United States since their 1993 peak, a pair of reports released Tuesday showed, adding fuel to Congress' battle over whether to tighten restrictions on firearms.

A study released Tuesday by the government's Bureau of Justice Statistics found that gun-related homicides dropped from 18,253 in 1993 to 11,101 in 2011. That's a 39 percent reduction.

Another report by the private Pew Research Center found a similar decline by looking at the rate of gun homicides, which compares the number of killings to the size of the country's growing population. It found that the number of gun homicides per 100,000 people fell from 7 in 1993 to 3.6 in 2010, a drop of 49 percent.

Both reports also found that non-fatal crimes involving guns were down by roughly 70 percent over that period. The Justice report said the number of such crimes diminished from 1.5 million in 1993 to 467,300 in 2011.

But perhaps because of the intense publicity generated by recent mass shootings such as the December massacre of 20 school children and six educators in Newtown, Conn., the public seems to have barely noticed the reductions in gun violence, the Pew study shows.

The non-partisan group said a poll it conducted in March showed that 56 percent of people believe the number of gun crimes is higher than it was two decades ago. Only 12 percent said they think the number of gun crimes is lower, while the rest said they think it remained the same or didn't know.

The data was released three weeks after the Senate rejected an effort by gun control supporters to broaden the requirement for federal background checks for more firearms purchases. Senate Democratic leaders have pledged to hold that vote again, perhaps by early summer, and gun control advocates have been raising public pressure on senators who voted "no" in hopes they will change their minds.

Sen. John Thune of South Dakota, a member of the Senate Republican leadership, said the figures show that gun control groups have emphasized the wrong approach to controlling firearms violence.

"That's what many of us have argued all along, is that focusing just exclusively on the guns is not the correct approach to this," he said. Thune said lawmakers should aim instead at preventing future mass killings by improving mental health programs and increasing the records that state governments send the federal background check system so the checks can do a better job of keeping guns from people who shouldn't have them.

Gun control supporters said the numbers have declined but remain too high, with U.S. rates of gun killings remaining far greater than most other nations.

"None of these studies change the impact of Newtown and other recent mass slayings, showing the need for common sense measures" restricting guns, Sen. Richard Blumenthal, D-Conn., said.

The Justice study said that in 2011, about 70 percent of all homicides were committed with firearms, mainly handguns.

The trend in firearm-related homicides is part of a broad nationwide decline in violent crime over past two decades, including incidents not involving firearms.

Both studies concluded that most of the decline in gun homicide rates occurred in the 1990s. The Justice report found that since 1999, the number of firearm homicides increased from 10,828 to 12,791 in 2006 before declining to 11,101 in 2011.

Though researchers differ over all the reasons why gun violence has declined, many attribute it to the aging of the baby boomers. The crime rate was higher in the 1960s and 1970s when many in that large generation were teenagers, an age when higher proportions of people commit crimes.

Crime rates dropped in the early 1980s as that generation aged, rose in the latter part of that decade as the use of crack cocaine grew, then dropped again in the 1990s as the nation's economy improved, analysts say.

The Pew report also said:

—The gun suicide rate is 6.3 per 100,000 people, and there were 19,392 suicides by firearms in 2010. That rate has declined more slowly than the firearms homicide rate, with 6 in 10 gun deaths now suicides, the highest proportion since at least 1981.

—More than 8 in 10 victims of gun homicides are men and boys.

—Fifty-five percent of gun homicide victims in 2010 were black, far beyond their 13 percent share of the population.

The Pew study chiefly used federal data from the federal Centers for Disease Control and Prevention, and the Justice Department's National Crime Victimization Survey, a household survey conducted by the Census Bureau.